Incidence, symptom clusters and determinants of post-acute COVID symptoms: a population-based surveillance in community-dwelling users of the COVID RADAR app

ObjectivesThis study aims to describe the incidence, symptom clusters and determinants of post-acute COVID symptoms using data from the COVID RADAR app in the Netherlands.DesignProspective cohort.SettingGeneral population in the Netherlands from April 2020 to February 2022.ParticipantsA total of 1478 COVID RADAR app users, with data spanning 40 days before to 100 days after positive SARS-CoV-2 test.Outcome measuresIncidence and duration of 10 new symptoms that developed during acute infection, defined as 10 days prior and 10 days after positive test. Clustering of these post-acute COVID symptoms and associations between factors known in the acute phase and 100-day symptom persistence.ResultsThe most frequent post-acute symptoms were cough, loss of smell or taste and fatigue. At 100 days postinfection, 86 (8%) participants still experienced symptoms. Three post-acute COVID symptom clusters were identified: non-respiratory (headache and fatigue; 49% of participants with post-acute COVID symptoms); olfactory (15%) and respiratory (8%). Vaccination was associated with a lower risk of post-acute COVID symptoms 100 days after infection, although CIs were wide (OR: 0.5; 95% CI: 0.2 to 1.5), but not with non-respiratory symptoms (OR: 1.0; 95% CI: 0.3 to 4.4). Severe acute disease increased the risk of post-acute COVID symptoms (OR: 1.4; 95% CI: 1.2 to 1.5; per additional acute symptom).ConclusionsIn this cohort of infected community-dwelling app users, 5%–10% experienced post-acute COVID symptoms. The symptoms cluster in several distinct entities, which differ in incidence, patient characteristics and vaccination effects. This suggests multiple mechanisms underlying the development of post-acute COVID symptoms.